The present invention relates generally to tape recording devices and more particularly to tape recording devices which can be made smaller because of saving space which a reel of an ordinary device takes.
A take-up reel and a supply reel of an ordinary magnetic tape device are placed side by side horizontally. Besides, said reels are so big in diameter that they take space so widely.
One device has solved this problem by saving the space of one reel, which is placed above the other reel like ones seen in U.S. Pat. Nos. 3,002,706, 3,189,289, 3,314,625, 3,662,937, 3,679,215 and 4,170,787 and USSR Pat. No. 291,234. However, this device has two problems.
The major problem is a transference problem of a tape. The magnetic tape travels from one reel to the other being placed above the other reel. Consequently, the tape has to travel from the bottom reel to the top reel. However, the tape can not be bent horizontally to the tape face, though it can be easily bent in perpendicular to the tape face. Therefore, it employs a taper type pully or an inclined pully in order to spiral the tape thereon. Thereby, the tape can travel from the bottom reel to the top reel as a direction the tape travels to is shifted. However, the angle which the tape travels from said pulley to a take-up reel is slightly different from the direction which said take-up reel takes up the tape to. Besides, the angle and the position of said inclined or taper type pulley need so much preciseness that it takes a lot of time to adjust them when the device is assembled because a small error of the angle or the position makes a big difference in the direction which the tape travels to. Moreover, the tape has to be set carefully so that when the device is to be operated as the tape is twisted on the pulley, which means the twist of the tape has no tolerance for the tape when tightly fitted the pulley. Therefore, any missetting of a tape shifts the direction which the tape travels to, so that the tape is not properly taken up into said take-up reel, which spoils the tape with important data. Perfect setting of the tape is especially required in order not to spoil the tape when the device is operated in a deep sea where nobody can get down.
Furthermore, the magnetic tape is coated with metal powder. Therfore, the edges of the magnetic tape are rough like a file or a sandpaper, which makes a groove in a tape guide made of even hard metal such as stainless steel, if the angle or the position of the taper type or inclined pulley is not accurate, and if it is used for long time. Thereby, a tape will be misguided, which will spoil the tape.
The minor problem is fracture of the shaft of said reels. In this device, one common shaft, which is a double shaft, has to hold two reels which constructs a double reel, as one reel is placed directly above the other. The device has not two solid shafts but one breakable double shaft, which is composed of two concentric layers for rotation of the supply reel and the take-up reel is different. Besides the reels are heavy. Consequently, one breakable double shaft has to hold two heavy reels with tape, Therfore, it easily breaks when it is greatly shocked.
Especially, it makes a great problem when it is operated in a deep sea in order to get important data therein. Because a distance between the surface and the bottom of a deep sea is so great, a magnetic tape device is dropped down very fast with a heavy weight in order to get to the sea bottom as soon as possible. Thereby, it is greatly shocked when it runs against the sea bottom. Moreover, it is greatly shocked when it comes back to the surface for the heavy weight is cut away be explosion. Even a small explosion shocks the device as it is in water. A device of another similar invention such as U.S. Pat. No. 3,135,475 employs a guide plate in order to shift the tape position. However, it also has the same difficulty as the above mentioned device because of an angle of the guide plate and also the double shaft problem. Another device of another invention relating to the present invention such as U.S. Pat. Nos. 3,642,227 and 3,314,625 employ synchronized pulleys in order to shift the tape position. However, it is impossible to drive a tape exactly at the same speed at each pulley because of inbalance of diameters of pulleys and so on, which causes tape damage. Only a film with a chain of holes and tooth-pulleys can accomplish it, but it needs a complicated mechanism, which causes higher costs.
The present invention has solved these problems by twisting a tape "between" pulleys. The device of the present invention employs a means not to spiral a tape but to twist a tape, so that the tape can travel anywhere without damage of tape, and so that the difficulty of adjustment of an angle of incline of a pulley at production is eliminated. Thereby, a take-up reel can be placed anywhere without relation to a supply reel, so that the reels can have their own solid shafts instead of a weak double reel. And the device of the present invention employs the means to twist the tape not "on" a pulley like a spiral means but "between" pulleys, so that tolerant twist can be made. Therby, the tape can properly taken up into the take-up reel.